TmEE's trick

TmEE's trick is writing to VRAM during hblank (which normally isn't allowed) by enabling fblank, performing the write, and then disabling fblank before hblank ends.

In 2020, 93143 tested this trick in order to transfer 20 bytes of data with HDMA during a single hblank. 9343 then tested this trick using an IRQ instead of HDMA, and was able to transfer 29 bytes per hblank.

Screenshot of the hvdma.sfc test ROM. TmEE's trick is activated halfway down the screen in order to change the "X" tile to a check mark.

Reference

• https://forums.nesdev.org/viewtopic.php?t=19896